Modification of alkaline lysis method for rapid plasmid DNA isolation

ABSTRACT Isolation of quality plasmid DNA from bacterial cells is critical in molecular biology experiments. Although efficient protocol for plasmid isolation are developed and standardized, rapid and cost effective protocols are desirable while handling a large number of samples. In present study we are reporting a simple procedure for extracting naked plasmid DNA which can be used for a large number of samples with sufficient purity. The method involves denaturation of high molecular weight chromosomal DNA using strong alkali, during neutralization process, chromosomal DNA renatures, and proteins denature to form an insoluble clot in the presence of choatropic agent guanidine hydrochloride, leaving plasmid DNA in the supernatant. The modified protocol which is less expensive compared to the commercial plasmid DNA isolation kit available, yields quality plasmid DNA. We tested the yield and quality of different kinds of plasmid extracted from bacteria. The results suggest that the protocol can be effectively used for molecular cloning, sequencing, and transfection.